cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-8 of 8 results.

A298684 Numbers i such that Fibonacci(i) is divisible by i, i+1, and i+2.

Original entry on oeis.org

60, 540, 660, 1200, 1320, 1620, 2160, 3060, 5580, 6120, 6600, 6720, 8100, 9180, 9240, 9600, 9720, 9900, 11160, 12240, 12300, 12600, 13200, 13440, 13680, 15120, 15360, 18300, 18480, 19440, 19800, 21000, 22500, 24480, 24840, 26880, 27360, 28920, 29400, 30240, 30780
Offset: 1

Views

Author

Alex Ratushnyak, Jan 24 2018

Keywords

Comments

A subsequence of A217738.

Crossrefs

Programs

  • Magma
    [n: n in [2..10^5] | IsZero(Fibonacci(n) mod (n)) and IsZero(Fibonacci(n) mod (n+1)) and IsZero(Fibonacci(n) mod (n+2))]; // Vincenzo Librandi, Jan 27 2018
  • Mathematica
    fQ[n_] := Mod[ Fibonacci@ n, {n, n +1, n +2}] == {0, 0, 0}; Select[60 Range@513, fQ] (* Robert G. Wilson v, Jan 26 2018 *)
  • Python
    from _future_ import division
    A298684_list, n, a, b = [], 1, 1, 1
    while len(A298684_list) < 1000:
        if not (a % (n*(n+1)*(n+2)//(1 if n % 2 else 2))):
            A298684_list.append(n)
        n += 1
        a, b = b, a+b # Chai Wah Wu, Jan 26 2018
    

A298685 Numbers i such that Fibonacci(i) is divisible by i, i+1, i+2, and i+3.

Original entry on oeis.org

540, 1200, 1620, 3060, 5580, 9180, 9900, 12600, 13440, 13680, 18300, 19440, 19800, 21000, 24480, 36900, 43200, 49680, 50220, 54120, 57240, 61560, 65880, 81180, 83700, 103680, 104160, 154080, 155520, 156060, 156240, 202440, 229320, 252000, 279000, 298200, 302940
Offset: 1

Views

Author

Alex Ratushnyak, Jan 24 2018

Keywords

Comments

A subsequence of A298684.

Crossrefs

Programs

  • Mathematica
    Select[Range[10^5], Function[{i, j}, AllTrue[i + Range[0, 3], Divisible[j, #] &]] @@ {#, Fibonacci@ #} &] (* Michael De Vlieger, Jan 28 2018 *)
  • PARI
    isone(n, k) = !(fibonacci(n) % (n+k));
    isok(n) = isone(n,0) && isone(n,1) && isone(n,2) && isone(n,3); \\ Michel Marcus, Jan 29 2018

A298686 Numbers i such that Fibonacci(i) is divisible by i+k for k=0,1,2,3,4.

Original entry on oeis.org

13440, 19440, 19800, 24480, 49680, 61560, 104160, 229320, 298200, 311040, 329400, 436800, 471240, 600600, 1202040, 1299600, 1468800, 1564920, 1702800, 2031120, 2352240, 2402400, 2499840, 2762760, 2805600, 2937600, 2962080, 3150840, 3262680, 3405600, 3843840
Offset: 1

Views

Author

Alex Ratushnyak, Jan 24 2018

Keywords

Comments

A subsequence of A298685.

Crossrefs

Programs

  • PARI
    isone(n, k) = !(fibonacci(n) % (n+k));
    isok(n) = isone(n,0) && isone(n,1) && isone(n,2) && isone(n,3) && isone(n,4); \\ Michel Marcus, Jan 28 2018

Extensions

More terms from Alois P. Heinz, Jan 25 2018

A298687 Numbers i such that Fibonacci(i) is divisible by i+k for k=0..5.

Original entry on oeis.org

13440, 19440, 329400, 600600, 2499840, 3150840, 5590200, 7660800, 69069000, 83980800, 96049800, 98385840, 175472640, 179663400, 237484800, 320498640, 330663600, 375396840, 404351640, 406380240, 429660000, 437940000, 505234800, 574585200, 635980800
Offset: 1

Views

Author

Alex Ratushnyak, Jan 24 2018

Keywords

Comments

A subsequence of A298686.

Crossrefs

Programs

  • Python
    p0 = 0
    p1 = 1
    for i in range(1,1000000):
      if p1 % i == 0 and p1 % (i+1) == 0 and p1 % (i+2) == 0:
         if p1 % (i+3) == 0 and p1 % (i+4) == 0 and p1 % (i+5) == 0:  print(i)
      p0, p1 = p1, p0+p1

Extensions

a(9)-a(25) from Chai Wah Wu, Jan 27 2018

A299155 Numbers i such that Fibonacci(i) is divisible by i+k for k=0..6.

Original entry on oeis.org

329400, 175472640, 808214400, 1367566200, 1928871000, 3433706640, 16109533440, 16916445000, 17847413640, 19507068000, 23163310800, 24961167000, 32645743200, 37263088800, 39803400000, 44915270400, 50238568800, 66072283200, 81924990840, 85368457440
Offset: 1

Views

Author

Chai Wah Wu, Feb 03 2018

Keywords

Comments

A subsequence of A298687.

Crossrefs

Programs

  • PARI
    fibomod(n,m) = lift(Mod([0,1;1,1],m)^(n+1))[1,1];
    isok(n) = prod(k=0,6,fibomod(n,n+k)==0); \\ Silvester Resnik, May 18 2018

Extensions

a(7)-a(20) from Silvester Resnik, May 18 2018

A298688 a(n) is the least i such that Fibonacci(i) is divisible by i+k for all k=0..n.

Original entry on oeis.org

1, 60, 60, 540, 13440, 13440, 329400, 175472640, 50238568800
Offset: 0

Views

Author

Alex Ratushnyak, Jan 24 2018

Keywords

Comments

a(0)..a(5) are first terms of sequences A023172, A217738, A298684, A298685, A298686, A298687.

Examples

			Least i such that Fibonacci(i) is divisible by i and i+1 (cf. A217738) is i=60, therefore a(1)=60.
Least i such that Fibonacci(i) is divisible by i, i+1, ..., i+5 (cf. A298687) is i=13440, therefore a(5)=13440.
		

Crossrefs

Extensions

a(7) from Alois P. Heinz, Jan 25 2018
a(6) inserted by Chai Wah Wu, Jan 26 2018
a(8) from Silvester Resnik, May 18 2018

A300555 Numbers i such that Fibonacci(i) is divisible by i+k for k = 0..7.

Original entry on oeis.org

175472640, 44915270400, 50238568800, 439287521400, 572836904640, 589596638400, 735284012400, 778042465200, 987189789600, 1261551677400, 1297640010240, 1307130728400, 1569978804240, 1979830125000, 2705598768600
Offset: 1

Views

Author

Silvester Resnik, May 19 2018

Keywords

Crossrefs

Programs

  • PARI
    fibomod(n, m) = lift(Mod([0, 1; 1, 1], m)^(n+1))[1, 1];
    isok(n) = prod(k=0, 7, fibomod(n, n+k)==0);

A303585 Numbers i such that Fibonacci(i) is divisible by i+k for k = 0..8.

Original entry on oeis.org

50238568800, 5824121940000, 46919196354240, 50564131254000, 80493123110400, 195778384956000, 307148642236800, 799863695270640
Offset: 1

Views

Author

Silvester Resnik, May 25 2018

Keywords

Crossrefs

Programs

  • PARI
    fibomod(n, m) = lift(Mod([0, 1; 1, 1], m)^(n+1))[1, 1];
    isok(n) = prod(k=0, 8, fibomod(n, n+k)==0);
Showing 1-8 of 8 results.